Sensor unblocking ramps

ABSTRACT

Shiftable gearing including spring loaded means and blocker means for effecting engagement of clutch teeth. In a transmission having a main shaft and at least one countershaft, and including pairs of shiftable gears arranged on and cooperatively between said shafts, there are provided spring loaded clutches for effecting connection to one of said shafts of a selected one gear of a selected one of said pairs of said gears upon the achievement of substantial synchronization between such gear and such shaft. Blockers are provided for protecting the clutch teeth from excessive wear during such shifting and malfunctioning of said blockers is prevented in part by providing light frictional drag means between each of said blockers and the portion of said clutches rotatable with said shaft and in part by angling the leading surfaces of the blocker teeth an amount sufficient to effect an unblocking under one limited set of conditions but insufficient to prevent blocking under normal operating conditions. Said drag acts axially to cause said blockers to bear against the gear cone and thereby to rotate therewith promptly upon the commencement of an engaging or clutching operation. Said angling enables said blockers to effect their own unblocking under certain special conditions of operation where the blockers otherwise tended to lock into blocking position but does not prevent proper operation thereof under normal operating conditions.

United States Patent [191 Richards Dec. 9, 1975 1 1 SENSOR UNBLOCKINGRAMPS [75] Inventor: Elmer A. Richards, Oshtemo, Mich.

[73] Assignee: Eaton Corporation, Cleveland, Ohio [22] Filed: Mar. 20,1974 [21] Appl. No.: 452,726

[52] US. Cl. 74/331; 74/339; 74/372; 192/53 E; 192/53 F; 192/4891 [51]Int. Cl. F16H 3/08; F16D 13/20; F16D 21/00 [58] Field of Search 74/331,372, 339; 192/4891, 53 F, 53 E Primary Examiner-Samuel Scott AssistantExaminerP. S. Lall Attorney, Agent, or Firm-Teagno & Toddy [57] ABSTRACTShiftable gearing including spring loaded means and blocker means foreffecting engagement of clutch teeth. In a transmission having a mainshaft and at least one countershaft, and including pairs of shiftablegears arranged on and cooperatively between said shafts, there areprovided spring loaded clutches for effecting connection to one of saidshafts of a selected one gear of a selected one of said pairs of saidgears upon the achievement of substantial synchronization between suchgear and such shaft. Blockers are provided for protecting the clutchteeth from excessive wear during such shifting and malfunctioning ofsaid blockers is prevented in part by providing light frictional dragmeans between each of said blockers and the portion of said clutchesrotatable with said shaft and in part by angling the leading surfaces ofthe blocker teeth an amount sufficient to effect an unblocking under onelimited set of conditions but insufficient to prevent blocking undernormal operating conditions. Said drag acts axially to cause saidblockers to bear against the gear cone and thereby to rotate therewithpromptly upon the commencement of an engaging or clutching operation.Said angling enables said blockers to effect their own unblocking undercertain special conditions of operation where the blockers otherwisetended to lock into blocking position but does not prevent properoperation thereof under normal operating conditions.

10 Claims, 9 Drawing Figures US. Patent 156491975 sheet 1 on 3,924,484

US. Patent Dec. 9 1975 Sheet 2 of 3 US. Patent Dec. 9 1975 Sheet 3 of33,924,484

SENSOR UNBLOCKING RAMPS FIELD OF THE INVENTION This invention relates toa shiftable change speed gear device and particularly relates to atransmission, preferably a multiple countershaft transmission, havingresiliently yieldable shifting mechanisms for substantially simplifyingshifting of the transmission and further having blocker means ofsimplified construction for improving the operation thereof.

BACKGROUND OF THE INVENTION In the design of transmissions, particularlyheavy duty transmissions such as used on trucks, there has existed for along time the problem of shifting the trans mission through the variousspeed ratios, which problem is even greater when the transmission isprovided with an auxiliary or range transmission section for increasingthe number of speed ratios. In most known transmissions, the shiftingprocess is either relatively difficult and/or the shifting mechanism isrelatively complex. Thus, there has been a continuing effort in thedesign of transmissions to improve the shifting, to improve the rapidityof shifting, to reduce the complexity of the shifting mechanism and toreduce its cost. Hence, without detracting from the operability ordesirability of many of the shifting mechanisms previously known, it maybe stated that in the present invention these general objectives areaccomplished to even a greater degree than has been previously possible.

Particularly, most known transmissions have necessarily utilizedsynchronizers, of which many different types are known, for causing thespeed of the jaw or toothed clutch members to be substantiallysynchronized prior to permitting their interengagement during a shiftingsequence from one speed ratio to another speed ratio. While the use ofsynchronizers does permit the shifting operation to be performed, theiruse, as is already known, imposes certain requirements of weight, spaceand power which it is desirable to ease or avoid entirely, if possible.

These and other problems incident to previously known transmissions wereset forth and acknowledged in my application Ser. No. 276,376, now US.Pat. No. 3,799,002 entitled Transmission with Resiliently Loaded MainShaft Gears assigned to the same assignee as the present application andapparatus was disclosed therein which effectively meets these problemswhile providing a reliable, effective and efficient transmission,particularly for heavy duty use.

While both forms of the invention disclosed in said application, namelythat using blockers and that not using blockers, are effective forcarrying out the objectives thereof, it has been noted that for theusual reasons both noise and clutch tooth wear can be minimized by theuse of blockers as set forth in said application and since the datethereof a considerable amount of further investigation has been carriedout related thereto, both for the simplifying of the blocker structureand for improving the operation thereof.

In this last connection, it was noted in the further development of theembodiment shown in said application using blockers that sometimes aftera period of neutral condition with the vehicle stopped it was impossibleto shift the auxiliary transmission in an upshift direction. This couldusually be cured by first shifting momentarily from neutral intoreverse, but this obviously was an inconvenient and a highly undesirabletechnique and it appreciably hampered the commercial acceptability of anotherwise highly satisfactory transmission.

In further development and study of this transmission, particularly withrespect to the problem just named, it was discovered that said problemoccurred when the front box of the transmission came into neutral withthe vehicle stopped and an upshift selected. Because of the previousmode of operation in a lower gear, the blocker can be unblocked for suchupshift only be reducing the speed of the main shaft which here, sinceit is in the case in question already stopped, can be accomplished only,as above noted, by momentarily reversing the main shaft.

In addition it was noted that during a compound shift the change inspeed of the main shaft caused by the other member involved in thesequence can cause inertia forces exceeding the random contact forces onthe blocker. This causes the blocker to change position during theinterval while the shaft is changing speed. When the second member ofthe sequence starts to move into position under this condition, theblocker immediately unblocks resulting in an undesirable presynchronousshift.

Accordingly it is an object of the present invention to provide atransmission having improved shifting structure for overcoming theabove-mentioned disadvantages. Particularly, it is an object of thepresent invention to provide:

1. A transmission having means to improve the ease of shifting, toimprove the rapidity of shifting without requiring large synchronizers,to reduce complexity of the mechanism and to reduce its cost.

2. A transmission, as aforesaid, which utilizes resilient means forcausing meshing engagement of the jaw clutch members after the desiredspeed synchronization has been achieved.

3. A transmission, as aforesaid, having the main shaft gears floatinglysupported relative to the main shaft by a plurality of countershaftgears so as to minimize the inertia of the main shaft:and includingclutch collars keyed to the main shaft for cooperation of the main shaftgears.

4. A transmission, as aforesaid, utilizing blockers for assisting ineffecting a smooth and noise-free shift and particularly for minimizingthe wear on the inter-engaging jaw clutch teeth.

5. To provide a transmission, as aforesaid, wherein the previouslyexisting above-described tendency to require momentary reverse operationbefore shifting out of an idling condition is eliminated.

6. To provide blockers of-such structure in relationship to othercomponents of the transmission as to eliminate the above-mentionedpreviously existing tendency for erroneous positioning of such blockerswith respect to the clutch components.

7. To provide a transmission and blocker arrangement wherein theblockers on the main shaft part of a jaw clutch will be subjected tosufficient axial drag as to cause same to bear against the gear cone andthus effect a rotative force exceeding the inertia forces occurringthereon and thereby to effect a proper positioning thereof.

8. To provide a blocker construction of simplified but yet strongerconstruction than previously known blockers of this general type andnature.

Other objects and purposes of the invention will become apparent topersons acquainted with devices of this type upon reading the followingspecification and inspecting the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings:

FIG. 1 is a cross-sectional view of a transmission utilizing blockers ofthe type disclosed and claimed in the above-mentioned application andout of which arose the need for this present invention, the maintransmission portion thereof being taken along the line II of FIG. 3 andthe auxiliary transmission portion thereof being taken along line IIA ofFIG. 3.

FIG. 2 is a cross-sectional view of said transmission takensubstantially along the line IIII of FIG. 3.

FIG. 3 is a sectional elevational view taken along the line III-III ofFIG. 1.

FIG. 4 is an enlarged fragmentary view of the jaw clutch structureutilized in the rightwardmost gear of FIGS. 1 and 2.

FIG. 5 is a sectional view taken on the line VV of FIG. 4.

FIG. 6 shows the components of the blocker fragmentarily in unwrappedcondition and positioned for unblocking.

FIG. 7 is a view similar to FIG. 6 showing the parts in synchronouscondition permitting shifting.

FIG. 8 is a view similar to FIG. 6 showing in solid lines the parts inone blocking condition and in broken lines the parts in the otherblocking condition.

FIG. 8 is an enlarged fragmentary detail of the blocker ring teeth takenfrom the same direction as shown in FIG. 5.

FIG. 9 is a view taken in the direction of the arrows IXIX in FIG. 8.

Referring now to the apparatus in more detail, it will be recognizedthat a detailed disclosure of both the structure and operation of thetransmission in question has been set forth and claimed in theabove-mentioned application and reference is therefore made thereto forsuch details. Same will, however, be briefly summarized herein at least,as to the form thereof with which the present invention is concerned,for purposes of convenient reference and clear understanding of thepresent invention.

SUMMARY OF THE INVENTION Insofar as concerns the integration of theblocker into the entire transmission system, the blockers are placedbetween the two relatively slidable portions or components of most orall of the transmission clutches and the usual friction means areprovided for causing the blocker to rotate with one thereof as saidclutch components respectively move toward each other during a clutchingprocedure. As same occurs, the blocker limits such relative axialmovement until substantial synchronism between the clutch elementsinvolved in a given shift is achieved.

In the present invention, the blocker and the other clutch element of agiven clutchable pair of clutch components are provided with slightlyangling leading faces on the blocker teeth to effect an unblocking wherethe main shaft is otherwise unconnected to any other main shaft gearsand hence at a minimum inertia. The angling of said blocker teeth is,however, insufficient to effect unblocking during a normal shift andhence will not interfere with the required function thereof during anormal shift. There is further provided means by which a significantaxial drag with a minimum of rotational drag is provided constantlybetween the blocker ring and the clutch element blocked thereby. Thus,said blocker ring will be axially urged upon axial movement of saidlast-named clutch element into engagement with the driving cone of theother clutch element and will thereby be held in proper position againstthe effect of its own inertia with respect to the gear associatedtherewith. This assures that the blocker will be in the desired positionprior to contactwith the blocking surface of the clutch.

The blocker element itself also contains advantageous features in thatthere is removed only one portion of one tooth of a clutch element andthe blocker ring is provided with a pair of teeth extending toward theclutch element from which a part of said one tooth has been removed.Said pair of teeth are of sufficient circumferential spacing to straddlethe remaining portion of said one tooth when synchronization is achievedfor effecting an unblocking condition but said blocker teeth arethemselves of circumferential dimension less than the spacing betweenthe teeth on said clutch element for permitting circumferential shiftingthereof and the creation of a blocking condition. Additional groups eachcomprising a partially removed tooth on the clutch component andcooperating teeth on the blocker ring may be provided as desired.

DETAILED DESCRIPTION Referring to the drawings, there is illustrated atransmission 11 having both a main transmission section 12 and a rangeor auxiliary transmission section 13, each of which has a plurality ofselectable ratios. The main and range sections are both suitablyenclosed by conventional housing means.

The transmission 11 includes an input shaft 16 supported adjacent itsrearward end by a bearing 17 and provided with an input gear 18nonrotatably connected thereto, as by splines. The input gear 18simultaneously drives a plurality of countershafts at equal speeds. Inthe illustrated embodiment, the transmission is provided with twocountershafts 21 and 22 (FIG. 2) disposed on diametrically oppositesides of the main shaft 23, which main shaft is coaxially aligned withthe input shaft 16 and is provided with a pilot portion 24 on itsforward end rotatably received within and supported by the rearward endof the input shaft 16.

Each of the countershafts 21 and 22 is provided with an identicalgrouping of countershaft gears 25, 26, 2'7, 28 and 29 thereon, whichgroupings form pairs of gears, such as the pair of gears 26, ofidentical size and number of teeth and disposed on diametricallyopposite sides of the main shaft 23.

A plurality of main shaft drive gears 31, 32, 33 and 34 encircle themain shaft and are selectively clutchable thereto one at a time byyieldable clutch mechanisms, as described in greater detail hereinafter.

The main shaft gears 31, 32 and 33 encircle the main shaft 23, are incontinuous meshing engagement with, and are floatingly supported by, thediametrically opposed pairs of countershaft gears 26, 27 and 28,respectively, which mounting means and the special advantages resultingtherefrom are explained in greater detail in US. Pat. Nos. 3,105,395 and3,335,6l6. The main shaft gear 34 is the reverse gear and is incontinuous meshing engagement with 'the pair of countershaft gears 29 bymeans of conventional intermediate gears (not shown). The forwardmostcountershaft gears 25 are continually meshed with and driven by theinput gear 18 for causing simultaneous rotation of the countershafts 21and 22 whenever the input shaft 16 is rotatably driven.

As illustrated in FIG. 1, the input gear 18 is connected to aconventional shift fork 39, which shift fork is controlled by the shiftrod 37 for permitting input gear 18 to be shifted axially forselectively permitting direct driving engagement between the input shaft16 and the main shaft 23.

The main shaft gears 31 and 32 are axially interconnected to form a gearpair and are connected to a conventional shift fork 36, the position ofthe shift fork 36 being controlled in a conventional manner by means ofan appropriate shift rod similar to rod 37. The main shaft gear pair31-32 is thus shiftable axially relative to the main shaft 23 inresponse to axial shifting of the fork 36 by said rod. However, thegears 31 and 32 are independently rotatable relative to one another. Ina similar manner, the main shaft gears 33 and 34 are also axiallyinterconnected so as to be axially shiftable as a pair by means of theshift fork 38, which shift fork is also controlled by appropriate shiftmeans. The main shaft gear pair 33-34 is likewise and simiarly axiallymovable relative to the main shaft 23.

Considering now the range section 13, said main shaft 23 extendsthereinto and is coaxially arranged with and piloted into an outputshaft 58 which is in turn supported within the housing 13 by suitablebearings generally indicated at 59. Said range section further includesa plurality of countershafts 66 and 67 (FIG. 3) each having an identicalgrouping of countershaft gears thereon, of which two appear at 68 and 69(FIG. 1). The first pair of countershaft gears 68 are disposeddiametrically opposite and in continuous meshing engagement with a mainshaft gear 71, which main shaft gear is floatingly supported by theforward pair of countershaft gears, one being the gear 68 forsubstantially concentrically encircling the main shaft 23. A furthermain shaft gear 72 is also floatingly and substantially concentricallysupported relative to the main shaft 23 by the rearward pair ofcountershaft gears, one being the gear 69. Shift forks 73 and 74,respectively, are provided for effecting the shifting of gears 71 and 72and said shift forks are operated by appropriate shift rods of which oneappears at 76 for operation by any desired means such as the pressurecylinder 77. Appropriate control means 78 of presently known type isprovided for properly effecting and interrelating the control of theshift means for the forward gears 18 and 31-34 and the range gears 71and 72.

The yieldable clutch structures are arranged between the shiftable mainshaft gears in both the main transmission and the range section and areprovided with resilient means for urging engagement thereof as set forthin detail in said above-mentioned application. While said clutch meansare not identical with each other, they are generally similar and henceinsofar as the pres ent invention is concerned, it will be sufficient todescribe only one of them in detail with the understanding that same maybe applied to the other clutch units without difficulty by anyoneskilled in the art. Therefore, for this purpose, referring to therearwardmost clutch unit, namely that positioned between the range gear72 and the main shaft 23, as illustrated in detail in FIG. 4, same isgenerally designated 41 and includes an annular clutch collar 42encircling the main shaft 23. The

'clutch collar 42 is provided with internal splines 43 which aredisposed within corresponding external splines 44 provided on the mainshaft 23 for interconnecting the clutch collar 42 to the main shaft 23for rotation therewith. However, the cooperating splines 43 and 44permit the clutch collar 42 to freely slide axially relative to theshaft 23. A stop ring 46 is seated within a suitable groove formed onthe external periphery of the shaft 23 and is disposed for contactingthe clutch collar 42 and limiting the axial movement thereof. The collar42 is normally resiliently urged by means of a spring 47 into abuttingengagement with the stop ring 46.

The clutch collar 42 is provided with external teeth 48 thereon whichare adapted to meshingly engage the internal teeth 50 provided on one ofthe main shaft gears, such as the gear 72. The teeth 48 on the clutchcollar 42 are tapered, as at 51, and in a similar manner the leadingedge of the teeth 50 on the main shaft gear 72 are similarly tapered asat 52. The confronting tapered conical'surfaces 51 and 52 each extend atan angle of preferably between 30 and 40 degrees relative to thelongitudinal axis of the main shaft 23. The exact degree of taper, andthe advantages thereof, are explained in detail in US. Pat. No.3,265,173. The other end of the spring 47 resiliently acts against afurther clutch collar 53 (FIG. 1) which collar is identical to thecollar 42 but is disposed so that it has the tapered leading ends of itsteeth facing in the opposite direction.

Further resilient, substantially identical, clutch assemblies areprovided for the other shiftable gear sets but same are set forth indetail in the above-mentioned application and hence further descriptionthereof is unnecessary here.

The invention as thus far referred to is set forth in more detail in theabove-mentioned application particularly in connection with FIGS. 1-5thereof and reference is invited thereto for further details. In suchapplication, it was stated that there are some instances whereinblockers are desirable, particularly for conditions of heavy load andconsequent very rapid changes in relative gear speeds, and it is to thisportion of said previous intention to which the present inventionrelates.

With this in mind, attention is now directed to the blockers shown inthe drawings herewith as incorporated into the clutch units as desiredfor operation therewith.

Referring again to FIG. 4, a selected number, here three, of the teeth48 are partially removed for permitting the presence of the blockingring as hereinafter further described. Such partial removal leaves,however, a shortened tooth 49 for cooperation with the blocking ring.

Referring now to the blockers, one thereof is indicated generally at 81and comprises a ring encircling the clutch component 42 and has anappropriate numher, here three pairs, of radially inward projections 82and 83 which when properly positioned will mate with the external teethabove mentioned. The inward projections or teeth 82 and 83 are contouredat their sides to lie snugly against adjacent ones of the teeth 48, arepositioned to project into the spaces between a partially removed tooth49 and the teeth 48 on each side thereof. Each pair of teeth 82 and 83are circumferentially of less dimension than the corresponding circumferential spaces defined by partially removed teeth 49. The space,however, between the inwardly projecting teeth 82 and 83 is only aclearance distance wider than the corresponding circumferentialdimension of the tooth 49 so that when properly aligned at synchronism(or more accurately, when the relative speeds of the clutch componentscross synchronism) the teeth 82 and 83 will straddle the tooth 49 andthe clutch component 42 can move axially through but not past blockerring 81 to effect engagement with its corresponding gear.

The end faces of said blocker teeth 82 and 83 are tapered (FIG. 9) withthe direction of taper being such that the cutback portion of each toothis on the side thereof facing the other of said two teeth. The amount ofsuch taper appears to be at optimum of about l2-l5 with respect to aplane perpendicular to the longitudinal direction of the tooth with anapparent feasible range of approximately 10 to 17. The amount of suchtooth face which is tapered should be sufficient to, but need not bemore than enough to, fully overlap the adjacent corner of the remainingportion 49 of the partially removed tooth.

On the radially inner side of the ring 81 there is provided an inwardlydirected groove 54 which receives an annular resilient ring 55 which isnormally of slightly less internal diameter than the external diameterof the teeth 48 so that when the parts are in the assembled conditionshown in FIG. 4 said ring 55 is distorted slightly outwardly whereby toexert a light but definite pressure against the external surfaces ofsaid teeth 48. Inasmuch as the ring 55 fits loosely and in only lightfrictional contact with the walls of the groove 48, this effects asignificant resistance to relative axial movement between the blockerring 81 and the clutch ring 42 but only an insignificant resistance torelative rotative movement therebetween.

A suitable conical surface 56 projects radially outwardly from theblocker ring 81 and is positioned for engagement with a similar conicalsurface 57 on a radially inner wall of the gear 72. The axial drag abovementioned is sufficient that the rotative driving effect of the surface57 onto the blocker 41 is much greater than whatever rotative resistancemay exist between the blocker 81 and the clutch ring 41. A stop ring 60limits movement of the blocker 81 away from the conical surface 57 whenthe clutch ring 41 moves out of engagement (leftwardly in FIG. 4).

The other two partially removed tooth corresponding to the tooth 49 areindicated at 49A and 49B and internally extending teeth on the blockerring corresponding to the teeth 82 and 83 are indicated at 82A and 83Afor cooperation with the partial tooth 49A and at 82B and 83B forcooperation with the partial tooth 4913.

The operation of the blocker 41 is generally similar to that of knownblockers. For example, assuming the gear 72 is rotating more rapidlythan the clutch member 41, which latter, of course, rotates at the samespeed as the main shaft 23, the blocker 81 will normally (ignoring forthe moment the effect of the ring 55) tend to rotate with the gear 72,hence lead the clutch component 41 and position the teeth 83, 83A and83B in a position to interfere with the partial teeth 49, 49A and 49B,respectively, to prevent clutching (rightward) movement of the clutchcomponent 42. However, as the shaft 23 accelerates and a condition ofsynchronism is approached, the inwardly projecting blocker teeth willbecome centered with the partial teeth on the periphery of the clutchcomponent 41 and upon reversal of relative speeds the blockers will nolonger block and the clutch component 41 will move into clutchingcondition in the usual manner.

Where ,the gear 72 is initially running slower than the shaft 23 theoperation will be generally silimar to that above described exceptingthat the blocker 81 will lag behind the clutch component 41 until thereoccurs a reversal of relative speeds at which blocking will cease andclutching will again be completed in a manner already well known forblocking devices.

Considering now the effect of the blocker rings as above describedincorporated into the system of the above-designated application asherein further set forth and described, it will be recognized that whenthe transmission is brought into a neutral condition and the vehiclestopped from a previous condition wherein the low speed gear 71 was indriving connection, and neutral condition is achieved by neutralizingthe gears of the front box, the gear 72 will have been running moreslowly than the shaft 23 and hence the blocker in rotating with theclutch component 42 will be running faster than the gear 72 andpositioned accordingly. This will remain true with the shaft 23stationary and hence the only way to move the blocker on the clutchcomponent 42 has in the past been to provide a momentary engagement ofthe reverse gear 34 in the front box to effect momentary reversal of theshaft 23 and thereby moving of the blocker to its open position forcompletion of the shift.

However, under the system of the invention, and with the main shaftfreed from engagement by all of the gear otherwise connectible thereto,shifting of the gear 72 may be initiated and the slanted ends of one ofthe teeth 82 or 83, and their counterparts on the remainder of theblocker ring, will engage the corresponding partial teeth 49. Theangling faces of the thereby engaged blocker teeth will effect a slightbut sufficient rotation of the clutch component 42 and the shaft 23connected therewith to effect unblocking. It will be noted, however,that the torque created by the relatively shallow angling of the face ofthe blocker teeth is relatively slight and will be effective only whenno other gearing is connected to the shaft 23 so that the inertia of thelatter is very low. When other gears are connected to the shaft 23 sothat an otherwise conventional shift is taking place, then the anglingof the face of the blocker teeth is too shallow to overcome the inertiaof such shaft and the blocking proceeds in a normal manner.

Considering now the effect of the compression or drag ring 55, it willbe recognized that when there is no appreciable axial pressurerightwardly, as appearing in FIG. 4, on the blocker ring 81, there willbe no appreciable friction between the conical surfaces 56 and 57 andhence no tendency for the blocker ring 81 to rotate with the gear 72.However, as the clutch ring 41 commences to move axially, rightwardly inFIG. 4, the axial drag provided by the drag ring 55 urges the blockingring 81 likewise axially to effect interengagement between the frictionsurfaces 56 and 57. Since the rotative driving force of the surface 57onto the blocker ring is greater than the rotative resistance betweenthe blocker ring and the clutch ring 41, the blocking ring 81 commencesrotating with the gear 72 and does so prior to contact between the teethof the blocker 81 and the teeth of the clutch 41. Same then functionsthereafter in a normal manner. On disengagement, the stop prevents theblocker 81 from following the clutch ring 41. l

Thus, the incorporation of the blocking ring as herein described intothe system of the above-identified application brings about the improvedoperation described in said application as resulting from the use of ablocking ring where heavy components and/or loads are involved butwithout experiencing the tendency to block improperly as describedabove. Further, with reference to the blocking ring as such, it will berecognized that the blocking ring herein described requires removal ofonly a single tooth at the selected tooth removal points around itscircumference and in fact does not require the removal even of theentirety of such single tooth. Thus, the resulting clutch system issubstantially stronger than those systems where multiple teeth areremoved at each such selected circumferential point. Further, theblocking ring itself is of extremely simple construction, yet sturdy andeffective for accomplishing the objects of the invention including thosespecifically set forth above.

While a specific embodiment of the invention has been set forth hereinfor illustrative purposes, the principles of the invention will berecognized as more broadly applicable and variations will be apparent tothose skilled in the art but which variations will be included withinthe scope of the hereinafter appended claims excepting as said claimsexpressly require otherwise.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:

1. In a transmission system including a main shaft and at least onecountershaft, multiple pairs of shiftable ratio gears arranged betweensaid main shaft and said countershaft, with jaw clutch devices forconnecting at least one of at least some of said pairs of gears to oneof said shafts and said jaw clutches including at least one resilientlyloaded jaw clutch element being constantly resiliently urged towardengagement position and positively limited in its response to suchurging, the improvement comprising;

a blocker ring positioned between said last-named jaw clutch element andthe gear with which it is operatively associated and first frictionmeans operative between said blocker ring and said jaw clutch elementproviding a significant axial drag between said blocker ring and saidjaw clutch element without providing appreciable relative rotationaldrag therebetween and second friction means effective for causingrotation of said blocker ring with said gear upon axial urging of saidblocker ring toward said gear in response to initiation of a clutchingmovement by said jaw clutch element toward said gear;

whereby said blocker ring will normally rotate with said gear uponinitiation of a clutching sequence and before axial engagement thereofby the teeth of said jaw clutch element.

2. The device of claim 1 wherein said first friction means includes aninternal groove within said blocker ring and a friction ring containedwithin said groove and bearing against a portion of the teeth of saidjaw clutch element.

3. The device of claim 2 wherein said friction ring is a split steelring of normal diameter slightly less than that of the cylinder definedby the peripheral surfaces of said jaw clutch teeth,

4. The device of claim 1 wherein said first friction means includes aninternal groove within said blocker i 10 ring and a friction ringcontained within said groove and bearing against the peripheral surfacesof the teeth of said jaw clutch element.

5. The device of claim 1 wherein said blocker ring has radiallyprojecting blocker teeth and said last named jaw clutch element hasradially projecting teeth arranged for interference with said blockerteeth upon relative axial movement therebetween when said blocker ringis in other than a condition of synchronous rotation with said jawclutch element and for passage axially therebetween when the rotativespeed of said blocker ring crosses that of said jaw clutch element.

6. The device of claim 5 wherein the end faces of said blocker teethfacing said interfering tooth of said jaw clutch element are sloped withrespect to a plane normal to the axis of said blocker ring.

7. The device of claim 6 wherein the slope of the faces of said blockerring teeth is sufficient to effect limited rotation of said jaw clutchelement when same is free from engagement with at least substantiallyall of the ratio gears of said transmission but insufficient to effectsuch rotation and unblocking during normal operation from one shiftedposition to another shifted position.

8. In a transmission system including a main shaft and at least onecountershaft, multiple pairs of shiftable ratio gears arranged betweensaid main shaft and said countershaft, with jaw clutch devices forconnecting at least one of at least some of said pairs of gears to oneof said shafts and said jaw clutches including at least one resilientlyloaded jaw clutch element being constantly resiliently urged towardengagement position and positively limited in its response to suchurging, the improvement comprising:

a blocker ring positioned between said last-named jaw clutch element andthe gear with which it is operatively associated, said blocker ringencircling said last-named jaw clutch element for normal rotationtherewith and first and second friction means effective for causingrotation of said blocker ring with said gear in response to initiationof a clutching movement by said jaw clutch element relative to saidgear, said first friction means effective to apply an axial force forengaging said second friction means without applying a significantrotational drag on said jaw clutch element in response to relative axialmovement between said blocker ring and said jaw clutch element;

said blocker ring having radially projecting blocker teeth and saidlast-named jaw clutch element having radially projecting teeth arrangedfor interference with said blocker teeth upon relatively axial movementtherebetween when said blocker ring is in other than a condition ofsynchronous rotation with said jaw clutch element and for passageaxially therebetween when the rotative speed of said blocker ringcrosses that of said jaw clutch element and the end faces of saidblocker teeth facing said interfering tooth of said jaw clutch elementbeing sloped 'with respect to a plane normal to the axis of said blockerring.

9. The device of claim 8 wherein the slope on the faces of said blockerring teeth is sufficient to effect limited rotation of said jaw clutchelement when same is free from engagement with at least substantiallyall of the ratio gears of said transmission but insufficient to effectsuch rotation and unblocking during normal opangle of such sloped faqeis approximately lO-l7 to a plane normal to the axis of Sal? blockerring.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3,924,484 Dated December 9 1915 InventO Ell-g ljcha'rrlc It is certifiedthat error appears in the above-identified patent and that said LettersPatent are hereby corrected as shown below:

Column 2, line 12, "be"should read by Column 3, Fig; 7 has been deletedentirely.

Column 3, the first Fig. 8 has been renumber as Fig. 7.

Signed and Scaled this thirteenth Day Of April 1976 [SEAL] Arrest:

RUTH C. MASON C. MARSHALL DANN Af l lirlg llf l't ('mnmissimu'ruj'lau'ms and T radcmarks

1. In a transmission system including a main shaft and at least onecountershaft, multiple pairs of shiftable ratio gears arranged betweensaid main shaft and said countershaft, with jaw clutch devices forconnecting at least one of at least some of said pairs of gears to oneof said shafts and said jaw clutches including at least one resilientlyloaded jaw clutch element being constantly resiliently urged towardengagement position and positively limited in its response to suchurging, the improvement comprising: a blocker ring positioned betweensaid last-named jaw clutch element and the gear with which it isoperatively associated and first friction means operative between saidblocker ring and said jaw clutch element providing a significant axialdrag between said blocker ring and said jaw clutch elemeNt withoutproviding appreciable relative rotational drag therebetween and secondfriction means effective for causing rotation of said blocker ring withsaid gear upon axial urging of said blocker ring toward said gear inresponse to initiation of a clutching movement by said jaw clutchelement toward said gear; whereby said blocker ring will normally rotatewith said gear upon initiation of a clutching sequence and before axialengagement thereof by the teeth of said jaw clutch element.
 2. Thedevice of claim 1 wherein said first friction means includes an internalgroove within said blocker ring and a friction ring contained withinsaid groove and bearing against a portion of the teeth of said jawclutch element.
 3. The device of claim 2 wherein said friction ring is asplit steel ring of normal diameter slightly less than that of thecylinder defined by the peripheral surfaces of said jaw clutch teeth. 4.The device of claim 1 wherein said first friction means includes aninternal groove within said blocker ring and a friction ring containedwithin said groove and bearing against the peripheral surfaces of theteeth of said jaw clutch element.
 5. The device of claim 1 wherein saidblocker ring has radially projecting blocker teeth and said last namedjaw clutch element has radially projecting teeth arranged forinterference with said blocker teeth upon relative axial movementtherebetween when said blocker ring is in other than a condition ofsynchronous rotation with said jaw clutch element and for passageaxially therebetween when the rotative speed of said blocker ringcrosses that of said jaw clutch element.
 6. The device of claim 5wherein the end faces of said blocker teeth facing said interferingtooth of said jaw clutch element are sloped with respect to a planenormal to the axis of said blocker ring.
 7. The device of claim 6wherein the slope of the faces of said blocker ring teeth is sufficientto effect limited rotation of said jaw clutch element when same is freefrom engagement with at least substantially all of the ratio gears ofsaid transmission but insufficient to effect such rotation andunblocking during normal operation from one shifted position to anothershifted position.
 8. In a transmission system including a main shaft andat least one countershaft, multiple pairs of shiftable ratio gearsarranged between said main shaft and said countershaft, with jaw clutchdevices for connecting at least one of at least some of said pairs ofgears to one of said shafts and said jaw clutches including at least oneresiliently loaded jaw clutch element being constantly resiliently urgedtoward engagement position and positively limited in its response tosuch urging, the improvement comprising: a blocker ring positionedbetween said last-named jaw clutch element and the gear with which it isoperatively associated, said blocker ring encircling said last-named jawclutch element for normal rotation therewith and first and secondfriction means effective for causing rotation of said blocker ring withsaid gear in response to initiation of a clutching movement by said jawclutch element relative to said gear, said first friction meanseffective to apply an axial force for engaging said second frictionmeans without applying a significant rotational drag on said jaw clutchelement in response to relative axial movement between said blocker ringand said jaw clutch element; said blocker ring having radiallyprojecting blocker teeth and said last-named jaw clutch element havingradially projecting teeth arranged for interference with said blockerteeth upon relatively axial movement therebetween when said blocker ringis in other than a condition of synchronous rotation with said jawclutch element and for passage axially therebetween when the rotativespeed of said blocker ring crosses that of said jaw clutch element andthe end faces of said blocker teeth facing said interfering tooth ofsaid jaw clutch element being sloped With respect to a plane normal tothe axis of said blocker ring.
 9. The device of claim 8 wherein theslope on the faces of said blocker ring teeth is sufficient to effectlimited rotation of said jaw clutch element when same is free fromengagement with at least substantially all of the ratio gears of saidtransmission but insufficient to effect such rotation and unblockingduring normal operation from one shifted position to another shiftedpostion.
 10. The apparatus defined in claim 8 wherein the angle of suchsloped face is approximately 10*-17* to a plane normal to the axis ofsaid blocker ring.